Oxygen evolution catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of oxygen evolution catalysts, and relates to an oxygen evolution catalyst and a preparation method and application thereof. The preparation method of the oxygen evolution catalyst comprises the following steps: 1) mixing a rare earth metal compound with a noble metal oxide to prepare a mixture; 2) sintering the mixture at a high temperature to obtain a rare earth metal-noble metal oxide; and 3) dispersing the rare earth metal-noble metal oxide in an aqueous solution of a sulfur source and urea, and heating to prepare the oxygen evolution catalyst. The porous surface functional layer is formed on the surface of the existing noble metal oxide catalyst, so that partial phase change of the surface of the noble metal oxide catalyst in an oxygen evolution reaction in the prior art is inhibited, and the stability of the noble metal oxide catalyst is enhanced; the rare earth metal element is doped in the noble metal oxide catalyst, so that the atom utilization rate of the existing noble metal oxide catalyst can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy materials and electrocatalytic technology, and particularly relates to an oxygen evolution catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Hydrogen has become a promising energy carrier due to its high mass specific energy density (142 MJ·kg -1 ). Hydrogen has high utilization efficiency and is a renewable energy source with zero carbon emissions during the hydrogen production process. Electrochemical water splitting from renewable energy sources such as solar energy or wind energy is considered a clean and efficient hydrogen production route.

[0003] Water splitting includes hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Four electrons (4OH - →2H2O + O2 + 4e - ) are kinetically slow compared to the two electrons involved in HER and require a larger overpotential value.

[0004] Iridium-based and ruthenium-based materials are typical OER catalysts, but their high cost and scarcity limit their wide application. Improving the atomic utilization rate of noble metal materials is an effective means to reduce costs. However, in an acidic system, compared with pure iridium dioxide (IrO2), most multi-metal iridium-based oxides have poor stability. The main reason is that other transition metals exhibit poor corrosion resistance and undergo dissolution phenomena in an acidic system, thereby causing significant surface reconstruction and reducing their stability. Summary of the Invention

[0005] In view of this, the present invention provides an oxygen evolution catalyst, a preparation method thereof, and an application thereof. By forming a corrosion-resistant porous structure on the surface of the IrO2 catalyst, the surface structure of the IrO2 catalyst is stabilized, partial phase transformation on the catalyst surface is inhibited, and its stability is enhanced.

[0006] Specifically, the present invention is realized through the following technical solutions.

[0007] According to a first aspect of the present invention, a preparation method of an oxygen evolution catalyst is provided, including the following steps:

[0008] 1) Mix a rare earth metal compound and a noble metal oxide to obtain a mixture;

[0009] 2) Sinter the mixture at a high temperature to obtain a rare earth metal-noble metal oxide.

[0010] 3) Disperse the rare earth metal-noble metal oxide in an aqueous solution of a sulfur source and urea, and heat it under a water bath condition to prepare the oxygen evolution catalyst.

[0011] In the above method for preparing the oxygen evolution catalyst, the rare earth metal compound and the noble metal oxide are mixed according to the equimolar ratio of the rare earth metal element and the noble metal element.

[0012] In the present invention, by mixing the rare earth metal compound and the noble metal oxide according to the equimolar ratio of the rare earth metal element and the noble metal element (i.e., 1:1), it is beneficial to form a pyrochlore-structured rare earth metal-noble metal oxide, namely, Lu2Ir2O7, during subsequent sintering.

[0013] In the above method for preparing the oxygen evolution catalyst, in step 1), the rare earth metal compound includes at least one of lutetium oxide (Lu2O3) and lutetium chloride (LuCl3).

[0014] In the above method for preparing the oxygen evolution catalyst, in step 1), the noble metal oxide includes one of iridium dioxide (IrO2) and ruthenium dioxide (RuO2).

[0015] In the above method for preparing the oxygen evolution catalyst, in step 1), after the rare earth metal compound and the noble metal oxide are first mixed and ground, an alkaline compound is added for a second mixing and grinding.

[0016] In the above method for preparing the oxygen evolution catalyst, in step 1), the addition amount of the alkaline compound is 1-5% of the total addition mass of the rare earth metal compound, the noble metal oxide, and the alkaline compound. Optionally, the addition amount of the alkaline compound is 3% of the total addition mass of the rare earth metal compound, the noble metal oxide, and the alkaline compound.

[0017] In the present invention, adding a small amount of alkaline compound is beneficial to obtaining an oxide (A2B2O7) with a pyrochlore structure during the sintering process, where A represents a rare earth metal element and B represents a noble metal element. For example, Lu2Ir2O7.

[0018] In the above method for preparing the oxygen evolution catalyst, in step 1), the mixing can adopt conventional mixing methods in the art. For example, mechanical grinding (such as ball milling), high-speed mixing, etc.

[0019] In the above method for preparing the oxygen evolution catalyst, in step 1), the average particle size of the powder of the rare earth metal compound is less than 1 μm.

[0020] In the above method for preparing the oxygen evolution catalyst, in step 1), the average particle size of the powder of the noble metal oxide is less than 1 μm.

[0021] In the above method for preparing the oxygen evolution catalyst, in step 1), the alkaline compound is added in the form of powder.

[0022] In the preparation method of the above oxygen evolution catalyst, in step 1), the alkaline compound includes KOH.

[0023] In the preparation method of the above oxygen evolution catalyst, in step 2), the rare earth metal-noble metal oxide is an oxide with a pyrochlore structure, abbreviated as A2B2O7, where A represents a rare earth metal element and B represents a noble metal element.

[0024] In the preparation method of the above oxygen evolution catalyst, in step 2), the temperature of the high-temperature sintering is at least 600 °C. Preferably, the temperature of the high-temperature sintering is 600-800 °C.

[0025] In the present invention, too high a sintering temperature in step 2) will cause the sintered particles to be too large, thereby increasing the difficulty of subsequent process operations.

[0026] In the preparation method of the above oxygen evolution catalyst, in step 2), the time of the high-temperature sintering is at least 12 hours. Optionally, the time of the high-temperature sintering is 12-24 h.

[0027] In the preparation method of the above oxygen evolution catalyst, in step 2), the Lu-Ir mixed powder is subjected to high-temperature sintering. After cooling to room temperature, it is sufficiently ground to obtain a rare earth metal-noble metal oxide (A2B2O7) with a pyrochlore structure, for example, Lu2Ir2O7.

[0028] In the preparation method of the above oxygen evolution catalyst, in step 3), the sulfur source includes any one of thiourea, carbon disulfide (CS2), and thioamide.

[0029] In the preparation method of the above oxygen evolution catalyst, in step 3), the mass ratio between the rare earth metal-noble metal oxide and the sulfur source is 26:1-4.

[0030] In the preparation method of the above oxygen evolution catalyst, in step 3), the aqueous solution concentration of the sulfur source is 0.5-1.5 mol / L, and can be 1 mol / L optionally.

[0031] In the preparation method of the above oxygen evolution catalyst, in step 3), the aqueous solution of the urea is 0.5 mol / L-1.25 mol / L.

[0032] In the preparation method of the above oxygen evolution catalyst, in step 3), the heating is carried out under water bath conditions.

[0033] In the preparation method of the above oxygen evolution catalyst, in step 3), the heating temperature is 80-100 °C.

[0034] In the preparation method of the above oxygen evolution catalyst, in step 3), the heating time is 4 to 8 h.

[0035] According to the second aspect of the present invention, an oxygen evolution catalyst is provided. The oxygen evolution catalyst includes a rare earth metal-noble metal oxide and a sulfide. The chemical formula of the oxygen evolution catalyst is S-A2B2O7, where A represents a rare earth metal element, B represents a noble metal element, S represents a sulfide, and A2B2O7 represents the rare earth metal-noble metal oxide; the sulfide exists in the surface structure layer of the rare earth metal-noble metal oxide.

[0036] In the above oxygen evolution catalyst, the rare earth metal-noble metal oxide has a pyrochlore structure.

[0037] Pyrochlore structure compounds can be regarded as ordered fluorite structure oxides with oxygen vacancies. The structure of pyrochlore structure oxides has certain oxygen vacancies, which have good stability at high temperatures and have potential application values in many fields. For example, it can be used as solid electrolytes, oxygen electrodes, and catalysts, etc.

[0038] In the above oxygen evolution catalyst, the rare earth metal element includes lutetium (Lu).

[0039] In the above oxygen evolution catalyst, the noble metal element includes at least one of iridium (Ir) and ruthenium (Ru).

[0040] In the above oxygen evolution catalyst, the oxygen evolution catalyst is prepared by using the preparation method of any one of the above oxygen evolution catalysts.

[0041] In the present invention, the oxygen evolution catalyst forms a porous surface functional layer of the oxygen evolution catalyst through sulfur and Lu2Ir2O7 with a pyrochlore structure. In the present invention, sulfur is combined with Lu2Ir2O7 with a pyrochlore structure, which not only improves the stability of the sulfur-containing oxide layer but also improves the utilization rate of the noble metal catalyst (Ir-containing catalyst).

[0042] The present invention uses a rare earth metal element (such as Lu) to modify the IrO2 catalyst, reducing the usage amount of the noble metal and at the same time improving the utilization rate of the noble metal catalyst.

[0043] According to the third aspect of the present invention, an application of the above oxygen evolution catalyst in the oxygen evolution reaction of the anode of electrolyzed water is provided.

[0044] In the above application, in the oxygen evolution reaction of electrolyzed water, the oxygen evolution catalyst is used as a catalyst for the oxygen evolution reaction of the anode of electrolyzed water.

[0045] When the oxygen evolution catalyst according to the present invention is used in the oxygen evolution reaction at the anode of electrolytic water, since the oxygen evolution catalyst has a Lu2Ir2O7 with a loose structure (i.e., pyrochlore structure) and a sulfur oxide layer (SO x ) on the surface of the Lu2Ir2O7 with a loose structure, during the oxygen evolution reaction, the loose surface structure allows the electrolyte to pass through, and at the same time, the SO x layer wrapped on the surface limits the structural phase change. This may be because during the process of the metal site valence increase, the SO x layer provides the required electrons and inhibits the degree of phase change, thereby improving the stability of the catalyst.

[0046] In the above application, by coating the slurry containing the oxygen evolution catalyst on the surface of the electrode substrate material to form an electrode containing the oxygen evolution catalyst coating, and applying the electrode containing the oxygen evolution catalyst coating as the anode in the electrolytic water reaction, the catalytic effect of the oxygen evolution catalyst in the electrolytic water oxygen evolution reaction is realized, and the stability of the oxygen evolution reaction is improved.

[0047] In the application of the above oxygen evolution catalyst in the field of electrolytic water reaction, the oxygen evolution catalyst S-Lu2Ir2O7 in a 0.1 mol / L HClO4 solution, when the current density is 100 mA / cm -2 , after 400 h, the voltage does not increase significantly.

[0048] In the present invention, without conflict, the above technical features can be freely combined to form new technical solutions.

[0049] The technical solution provided by the present invention has the following beneficial technical effects compared with the prior art:

[0050] 1) The present invention inhibits partial phase change on the surface of the IrO2 catalyst in the oxygen evolution reaction by forming a porous surface functional layer, enhancing its stability.

[0051] 2) The present invention can improve the atomic utilization rate of the existing IrO2 catalyst by doping the noble metal Lu in the IrO2 catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present invention, and are used together with the specification to explain the principles of the present invention.

[0053] Figure 1 It is the SEM image of the oxygen evolution catalyst product prepared in Example 1 of the present invention.

[0054] Figure 2XRD patterns of the target products prepared in Examples 1-3 of the present invention, where the vertical axis is intensity and the horizontal axis is 2θ degrees.

[0055] Figure 3 Potential-time curves of the products prepared in Examples 1-3 of the present invention in the oxygen evolution reaction (OER). The reaction conditions are as follows: the cathode is a Pt mesh, the anode is an electrode coated with the product prepared in Examples 1-3, the electrolyte is 0.1 mol / L HClO4 solution, and the current density is 100 mA / cm -2 。 Detailed implementation manners

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0057] According to some embodiments of the first aspect of the present invention, a method for preparing an oxygen evolution catalyst is provided, including the following steps:

[0058] 1) Mix a rare earth metal compound and a noble metal oxide to obtain a mixture powder;

[0059] 2) Sinter the mixture powder at a high temperature to obtain a rare earth metal-noble metal oxide.

[0060] 3) Heat the rare earth metal-noble metal oxide and a sulfur source to prepare the oxygen evolution catalyst.

[0061] According to some specific embodiments of the first aspect of the present invention, the rare earth metal compound and the noble metal oxide are mixed in an equimolar ratio of rare earth metal elements to noble metal elements.

[0062] In the present invention, by mixing the rare earth metal compound and the noble metal oxide in an equimolar ratio of rare earth metal elements and noble metal elements (i.e., 1:1), it is beneficial to form a pyrochlore-structured rare earth metal-noble metal oxide, such as lutetium iridium oxide (Lu2Ir2O7), during subsequent sintering.

[0063] According to some specific embodiments of the first aspect of the present invention, in step 1), the rare earth metal compound includes at least one of lutetium oxide (Lu2O3) and lutetium chloride (LuCl3).

[0064] In some specific embodiments of the first aspect of the present invention, in step 1), the noble metal oxide includes one of iridium dioxide (IrO2) and ruthenium dioxide (RuO2).

[0065] In some specific embodiments of the first aspect of the present invention, in step 1), after the rare earth metal compound and the noble metal oxide are first mixed and ground, an alkaline compound is added for a second mixing and grinding.

[0066] In some specific embodiments of the first aspect of the present invention, in step 1), the addition amount of the alkaline compound is 1-5% (for example, 2%, 3% or 4%) of the total addition mass of the rare earth metal compound, the noble metal oxide and the alkaline compound. Optionally, the addition amount of the alkaline compound is 3% of the total addition mass of the rare earth metal compound, the noble metal oxide and the alkaline compound.

[0067] In the present invention, adding a small amount of alkaline compound (such as KOH) is beneficial to obtaining Lu2Ir2O7 with a pyrochlore structure during the sintering process.

[0068] In some specific embodiments of the first aspect of the present invention, in step 1), the mixing can adopt conventional mixing methods in the art. For example, mechanical grinding (such as ball milling), high-speed mixing, etc.

[0069] In some specific embodiments of the first aspect of the present invention, in step 1), the average particle size of the rare earth metal compound powder is less than 1 μm.

[0070] In some specific embodiments of the first aspect of the present invention, in step 1), the average particle size of the noble metal oxide powder is less than 1 μm.

[0071] In some specific embodiments of the first aspect of the present invention, in step 1), the alkaline compound is added in the form of powder;

[0072] In some specific embodiments of the first aspect of the present invention, in step 1), the alkaline compound includes KOH.

[0073] In some specific embodiments of the first aspect of the present invention, in step 2), the rare earth metal-noble metal oxide is an oxide with a pyrochlore structure, abbreviated as A2B2O7, where A represents a rare earth metal element and B represents a noble metal element.

[0074] In some specific embodiments of the first aspect of the present invention, the rare earth metal includes lutetium (Lu).

[0075] According to some specific embodiments of the first aspect of the present invention, the noble metal element includes at least one of iridium (Ir) and ruthenium (Ru).

[0076] According to some specific embodiments of the first aspect of the present invention, in step 2), the temperature of the high-temperature sintering is at least 600 °C. Preferably, the temperature of the high-temperature sintering is 600 - 800 °C (for example, 650 °C, 700 °C, 750 °C or 780 °C).

[0077] In the present invention, the sintering temperature should not exceed 800 °C, which will cause the sintered particles to be too large.

[0078] According to some specific embodiments of the first aspect of the present invention, in step 2), the time of the high-temperature sintering is at least 12 hours. Optionally, the time of the high-temperature sintering is 12 - 24 h (for example, 13 h, 14 h, 15 h, 16 h, 18 h, 20 h or 22 h).

[0079] According to some specific embodiments of the first aspect of the present invention, in step 2), after the mixture powder is sintered at high temperature and cooled to room temperature, it is sufficiently ground to obtain a rare earth metal-noble metal oxide with a pyrochlore structure, such as Lu2Ir2O7.

[0080] According to some specific embodiments of the first aspect of the present invention, in step 3), the rare earth metal-noble metal oxide is dispersed in an aqueous solution of a sulfur source and urea, and heated under a water bath condition to prepare the oxygen evolution catalyst.

[0081] According to some specific embodiments of the first aspect of the present invention, in step 3), the sulfur source includes any one of thiourea, carbon disulfide (CS2) and thioamide.

[0082] According to some specific embodiments of the first aspect of the present invention, in step 3), the mass ratio between the rare earth metal-noble metal oxide and the sulfur source is 26:1 - 4 (for example, 26:2 or 26:3).

[0083] According to some specific embodiments of the present invention, in step 3), the concentration of the aqueous solution of the sulfur source is 0.5 - 1.5 mol / L (for example, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, 1.1 mol / L, 1.3 mol / L or 1.4 mol / L).

[0084] According to some specific embodiments of the present invention, in step 3), the aqueous solution of urea is 0.5 to 1.25 mol / L (for example, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, 1.1 mol / L or 1.2 mol / L).

[0085] In the present invention, urea decomposes into CO2 and NH3 during the synthesis process in step 3). The solubility of CO2 in water is weaker than that of NH3. Therefore, urea can provide an alkaline environment for the chemical reaction, which is beneficial to the sulfidation reaction, and partially converts the surface oxide of the rare earth metal-noble metal oxide into metal sulfide.

[0086] In the above method for preparing an oxygen evolution catalyst, in step 3), the heating is carried out under a water bath condition.

[0087] In the above method for preparing an oxygen evolution catalyst, in step 3), the heating temperature is 80 to 100 °C (85 °C, 90 °C or 95 °C).

[0088] In the present invention, heating by a water bath can accelerate the reaction between the rare earth metal-noble metal oxide and the sulfur source. However, too high a water bath temperature is not conducive to the complete conversion of the surface oxide of the rare earth metal-noble metal oxide into metal sulfide, thus being not conducive to obtaining an oxygen evolution catalyst with excellent performance.

[0089] In the above method for preparing an oxygen evolution catalyst, in step 3), the heating time is 4 to 8 h (for example, 5 h, 6 h or 7 h).

[0090] According to some embodiments of the second aspect of the present invention, an oxygen evolution catalyst is provided. The oxygen evolution catalyst includes a rare earth metal-noble metal oxide and a sulfide. The chemical formula of the oxygen evolution catalyst is S-A2B2O7, where A represents a rare earth metal element, B represents a noble metal element, S represents a sulfide, and A2B2O7 represents the rare earth metal-noble metal oxide; the sulfide exists in the surface structure layer of the rare earth metal-noble metal oxide.

[0091] According to some embodiments of the second aspect of the present invention, the rare earth metal-noble metal oxide has a pyrochlore structure.

[0092] Pyrochlore structure compounds can be regarded as ordered fluorite structure oxides with oxygen vacancies. The structure of pyrochlore structure oxides has certain oxygen vacancies, which have good stability at high temperatures and have potential application values in many fields. For example, it can be used as a solid electrolyte, an oxygen electrode and a catalyst, etc.

[0093] According to some embodiments of the second aspect of the present invention, the rare earth metal element includes lutetium (Lu).

[0094] According to some embodiments of the second aspect of the present invention, the noble metal element includes at least one of iridium (Ir) and ruthenium (Ru).

[0095] According to some embodiments of the second aspect of the present invention, the oxygen evolution catalyst is prepared by using the preparation method of any one of the above-mentioned oxygen evolution catalysts.

[0096] In the present invention, the oxygen evolution catalyst forms a porous surface functional layer of the oxygen evolution catalyst through sulfur and Lu2Ir2O7 having a pyrochlore structure. The present invention combines sulfur with Lu2Ir2O7 having a pyrochlore structure, which not only improves the stability of the sulfur-containing oxide layer but also improves the utilization rate of the noble metal catalyst (Ir-containing catalyst).

[0097] The present invention uses a rare earth metal element (such as Lu) to modify the IrO2 catalyst, reducing the usage amount of the noble metal while improving the utilization rate of the noble metal catalyst.

[0098] According to some embodiments of the third aspect of the present invention, there is provided an application of the above-mentioned oxygen evolution catalyst in the field of electrolytic water reaction.

[0099] According to some specific embodiments of the third aspect of the present invention, in the field of electrolytic water reaction, the oxygen evolution catalyst S-Lu2Ir2O7 is used as a catalyst for electrolytic water oxygen evolution reaction.

[0100] According to some specific embodiments of the present invention, by coating a slurry containing the oxygen evolution catalyst on the surface of an electrode substrate material, an electrode containing the oxygen evolution catalyst coating is formed, and the electrode containing the oxygen evolution catalyst coating is applied as an anode in the water electrolysis reaction to improve the stability of the oxygen evolution reaction.

[0101] According to some specific embodiments of the present invention, the oxygen evolution catalyst S-Lu2Ir2O7 is in a 0.1 mol / L HClO4 solution, and the current density is 100 mA / cm -2 Under this condition, after 400 h, the voltage does not increase significantly.

[0102] Example 1

[0103] A preparation method of an oxygen evolution catalyst includes the following steps:

[0104] S1: Uniformly mix and grind 1 mmol of Lu2O3 with an average particle size of less than 1 μm and 2 mmol of IrO2, add 20 mg of KOH, and mix and grind for the second time to obtain a Lu-Ir mixed powder, wherein the addition amount of KOH is 3% of the total mass of Lu2O3, IrO2, and KOH;

[0105] S2: Place the Lu-Ir mixed powder in step S1 in a muffle furnace, sinter at 600 °C for 12 h, and after cooling to room temperature, grind it again thoroughly to obtain Lu2Ir2O7 powder;

[0106] S3: Disperse the Lu2Ir2O7 powder in step S2 in 40 ml of deionized water, add 0.04 mol of thiourea and 0.05 mol of urea, and heat and stir at 90 °C under a water bath condition for 5 h to obtain the S-Lu2Ir2O7 oxygen evolution catalyst.

[0107] Example 2

[0108] A preparation method of an oxygen evolution catalyst, comprising the following steps:

[0109] S1: Uniformly mix and grind 1 mmol of Lu2O3 with an average particle size of less than 1 μm and 2 mmol of IrO2, add 20 mg of KOH, and grind them again for secondary mixing to obtain Lu-Ir mixed powder, wherein the addition amount of KOH is 3% of the total mass of Lu2O3, IrO2, and KOH;

[0110] S2: Place the Lu-Ir mixed powder in step S1 in a muffle furnace, sinter at 600 °C for 12 h, and after cooling to room temperature, grind it again thoroughly to obtain Lu2Ir2O7 powder;

[0111] S3: Take 20 mg of the Lu2Ir2O7 powder prepared in step S2 and disperse it in 40 ml of deionized water, add 0.01 mol of thiourea and 0.05 mol of urea, and heat and stir at 90 °C under a water bath condition for 5 h to obtain the S-Lu2Ir2O7 oxygen evolution catalyst.

[0112] Example 3

[0113] A preparation method of an oxygen evolution catalyst, comprising the following steps:

[0114] S1: Uniformly mix and grind 1 mmol of Lu2O3 with an average particle size of less than 1 μm and 2 mmol of IrO2, add 20 mg of KOH, and grind them again for secondary mixing to obtain Lu-Ir mixed powder, wherein the addition amount of KOH is 3% of the total mass of Lu2O3, IrO2, and KOH;

[0115] S2: Place the Lu-Ir mixed powder in step S1 in a muffle furnace, sinter at 600 °C for 12 h, and after cooling to room temperature, grind it again thoroughly to obtain Lu2Ir2O7 powder;

[0116] S3: Disperse 20 mg of the Lu2Ir2O7 powder prepared in step S2 in 40 ml of deionized water, add 0.05 mol of urea, and heat and stir for 5 h under the condition of a 90 °C water bath to obtain the S-Lu2Ir2O7 oxygen evolution catalyst.

[0117] Comparative Example 1

[0118] A preparation method of an oxygen evolution catalyst includes the following steps:

[0119] S1: Uniformly mix and grind 1 mmol of Lu2O3 with an average particle size less than 1 μm and 2 mmol of IrO2 to obtain a Lu-Ir mixed powder;

[0120] S2: Place the Lu-Ir mixed powder prepared in step S1 in a muffle furnace, sinter at 600 °C for 12 h, and after cooling to room temperature, grind it again sufficiently to obtain a Lu-Ir oxide powder;

[0121] S3: Take 20 mg of the Lu-Ir oxide powder prepared in step S2 and disperse it in 40 ml of deionized water, add 0.04 mol of thiourea and 0.05 mol of urea, and heat and stir for 5 h under the condition of a 90 °C water bath to obtain a solid product.

[0122] In this comparative example, since there is no KOH in the preparation of the Lu-Ir mixed powder in step S1, the Lu-Ir oxide powder prepared in step S2 does not have a pyrochlore structure, so a Lu2Ir2O7 oxygen evolution catalyst with a pyrochlore structure having sulfide on the surface cannot be obtained during the sulfidation treatment in step S3, that is, the S-Lu2Ir2O7 oxygen evolution catalyst cannot be obtained.

[0123] Structure Characterization

[0124] Use a scanning electron microscope and an XRD instrument to detect the micro-morphology and structure of the oxygen evolution catalyst products prepared in Examples 1-3. Figure 1 The SEM image of the oxygen evolution catalyst product prepared in Example 1 is shown, Figure 2 The XRD patterns of the oxygen evolution catalyst products prepared in Examples 1-3 are shown.

[0125] From Figure 1 it can be seen that the oxygen evolution catalyst product prepared in Example 1 has a loose structure, and a complex network structure formed by sulfide exists on the surface of this loose structure.

[0126] The oxygen evolution catalyst products prepared in Examples 2 and 3 also have a structure similar to that of the oxygen evolution catalyst product prepared in Example 1, that is, the oxygen evolution catalyst product has a loose structure, and a complex network structure formed by sulfide exists on the surface of this loose structure.

[0127] From Figure 2 It can be seen that the oxygen evolution catalyst products prepared in Examples 1-3 have the same crystal structure, and this crystal structure is the pyrochlore structure. That is, the Lu2Ir2O7 powder prepared in Examples 1-3 has the pyrochlore structure.

[0128] Comprehensively Figure 1 and Figure 2 It can be known that the finally obtained S-Lu2Ir2O7 oxygen evolution catalyst in Examples 1-3 has a loose pyrochlore structure, and the oxides on the surface of this loose pyrochlore structure are converted into a porous sulfide network structure through a sulfidation reaction.

[0129] Application Example

[0130] Using the products prepared in Examples 1-3 as coating materials to coat the surface of the electrode in the oxygen evolution reaction, an electrode with the above product coating is prepared, and using this electrode as the anode, the stability of the electrode containing this electrode in the oxygen evolution reaction is tested.

[0131] Figure 3 Shows the voltage-time curve of the products prepared in Examples 1-3 of the present invention in the oxygen evolution reaction (OER). Among them, the reaction conditions are: the cathode is a Pt mesh, the anode is an electrode containing the oxygen evolution catalyst product coating prepared in Examples 1-3, the electrolyte is 0.1 mol / HClO4 solution, and the current density is 100 mA / cm -2 .

[0132] From Figure 3 It can be seen that when the oxygen evolution catalysts with pyrochlore structure prepared in Examples 1 and 2 are used as the electrode coating materials for the oxygen evolution reaction, the voltage of the electrode with the oxygen evolution catalyst coating obtained remains basically unchanged with the migration of time in the oxygen evolution reaction. Among them, for the S-Lu2Ir2O7 oxygen evolution catalyst prepared in Example 1, in a 0.1 mol / L HClO4 electrolyte, when the current density is 100 mA / cm -2 When performing an electrochemical performance test for 400 h, the voltage does not increase significantly. In Example 3, since the product prepared does not contain sulfur, the coated electrode prepared with this product as the coating material has a gradually increasing voltage with the migration of time in the oxygen evolution reaction, which indicates that the electrode with the sulfur-free Lu2Ir2O7 oxygen evolution catalyst coating prepared in this example is unstable. Thus, it can be seen that the presence of the S-Lu2Ir2O7 oxygen evolution catalyst coating prepared according to the technical solution of the present invention can effectively improve the electrolytic stability of the electrode material.

[0133] Therefore, according to the technical solution of the present invention, noble metal Lu is doped into the IrO2 catalyst to prepare Lu2Ir2O7 powder with a pyrochlore structure. Then, the Lu2Ir2O7 powder is subjected to a sulfidation reaction to form a porous loose surface functional layer containing a sulfide network. Due to the porous sulfide network loose surface functional layer, the obtained oxygen evolution catalyst can inhibit partial phase changes occurring on the surface of the IrO2 catalyst in the oxygen evolution reaction in the prior art, thereby enhancing the stability of the electrode with the oxygen evolution catalyst coating during the electrolytic water oxygen evolution reaction. Therefore, by doping noble metal Lu into the IrO2 catalyst to form Lu2Ir2O7 with a pyrochlore structure and then subjecting it to a sulfidation reaction, the oxygen evolution catalyst obtained by the present invention can improve the atomic utilization rate of the existing IrO2 catalyst.

[0134] In summary, when the oxygen evolution catalyst according to the present invention is used in the electrolytic water anodic oxygen evolution reaction, since the oxygen evolution catalyst has a loose structure of Lu2Ir2O7 and a sulfur oxide layer (SO x ) on the surface of the loose structure of Lu2Ir2O7, during the oxygen evolution reaction, the loose surface structure allows the electrolyte to pass through, and at the same time, the surface-coated SO x layer restricts the structural phase change. This may be because during the process of the metal site valence increase, the SO x layer provides the required electrons, inhibits the degree of phase change, and thus improves the stability of the catalyst.

[0135] Although this specification contains many specific implementation details, these should not be construed as limiting the scope of any invention or the scope of what is claimed, but are mainly used to describe the features of specific embodiments of a particular invention. Certain features described in multiple embodiments in this specification can also be combined and implemented in a single embodiment. On the other hand, various features described in a single embodiment can also be separately implemented in multiple embodiments or implemented in any suitable sub-combination. In addition, although features may function in certain combinations as described above and are even initially claimed as such, one or more features from the claimed combination can be removed in some cases, and the claimed combination can be directed to a sub-combination or a variant of the sub-combination.

[0136] It should be noted that in this article, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such a process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, article or device including the said element.

[0137] The above are only specific embodiments of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. The present invention will not be limited to these embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A preparation method of an oxygen evolution catalyst, characterized in that, The preparation method includes the following steps: 1) Mix a rare earth metal compound and a noble metal oxide to obtain a mixture; 2) Sinter the mixture at a high temperature to obtain a rare earth metal-noble metal oxide; 3) Disperse the rare earth metal-noble metal oxide in an aqueous solution of a sulfur source and urea, and heat to prepare the oxygen evolution catalyst.

2. The preparation method of the oxygen evolution catalyst according to claim 1, wherein, The rare earth metal compound and the noble metal oxide are mixed in an equimolar ratio of rare earth metal elements to noble metal elements.

3. The preparation method of the oxygen evolution catalyst according to claim 1, characterized in that, In step 1), the rare earth metal compound includes at least one of lutetium trioxide and lutetium trichloride, and the noble metal oxide includes one of iridium dioxide and ruthenium dioxide.

4. The preparation method of the oxygen evolution catalyst according to claim 1, wherein, In step 1), after the rare earth metal compound and the noble metal oxide are first mixed and ground, an alkaline compound is added for a second mixing and grinding.

5. The preparation method of the oxygen evolution catalyst according to claim 4, wherein, In step 1), the addition amount of the alkaline compound is 1-5% of the total addition mass of the rare earth metal compound, the noble metal oxide, and the alkaline compound.

6. The preparation method of the oxygen evolution catalyst according to claim 1, characterized in that, In step 1), the average particle size of the powder of the rare earth metal compound is less than 1 μm; the average particle size of the powder of the noble metal oxide is less than 1 μm.

7. The preparation method of the oxygen evolution catalyst according to claim 4, wherein In step 1), the alkaline compound is added in the form of powder; the alkaline compound includes KOH.

8. The preparation method of the oxygen evolution catalyst according to claim 1, characterized in that, In step 2), the temperature of the high-temperature sintering is 600-800 °C, and the high-temperature sintering time is at least 12 hours.

9. The preparation method of the oxygen evolution catalyst according to claim 1, wherein, In step 2), the rare earth metal-noble metal oxide is an oxide with a pyrochlore structure, abbreviated as A2B2O7, where A represents a rare earth metal element and B represents a noble metal element.

10. The preparation method of the oxygen evolution catalyst according to claim 1, wherein In step 2), after the mixture is sintered at a high temperature and cooled to room temperature, it is sufficiently ground to obtain a rare earth metal-noble metal oxide.

11. The preparation method of the oxygen evolution catalyst according to claim 1, characterized in that, In step 3), the sulfur source includes any one of thiourea, carbon disulfide, and thioamide.

12. The preparation method of the oxygen evolution catalyst according to claim 1, wherein, In step 3), the mass ratio between the rare earth metal-noble metal oxide and the sulfur source is 26:1-4.

13. The preparation method of the oxygen evolution catalyst according to claim 1, characterized in that, In step 3), the concentration of the aqueous solution of the sulfur source is 0.5-1.5 mol / L; the aqueous solution of urea is 0.5 mol / L-1.25 mol / L.

14. The preparation method of the oxygen evolution catalyst according to claim 1, characterized in that, In step 3), the heating is carried out under a water bath condition, the heating temperature is 80-100 °C, and the heating time is 4-8 h.

15. An oxygen evolution catalyst, characterized in that, The oxygen evolution catalyst includes a rare earth metal-noble metal oxide and a sulfide. The chemical formula of the oxygen evolution catalyst is S-A2B2O7, where A represents a rare earth metal element, B represents a noble metal element, S represents a sulfide, and A2B2O7 represents the rare earth metal-noble metal oxide; the sulfide exists in the surface structure layer of the rare earth metal-noble metal oxide.

16. The oxygen evolution catalyst according to claim 15, wherein In the oxygen evolution catalyst, the rare earth metal-noble metal oxide has a pyrochlore structure.

17. The oxygen evolution catalyst according to claim 15, characterized in that, The rare earth metal element includes lutetium, and the noble metal element includes at least one of iridium (Ir) and ruthenium (Ru).

18. The oxygen evolution catalyst according to any one of claims 15-17, characterized in that, The oxygen evolution catalyst is prepared by using the preparation method of the oxygen evolution catalyst according to any one of claims 1-14.

19. Use of an oxygen evolution catalyst according to any one of claims 15 - 18 in the field of oxygen evolution reaction in electrolytic water 20. Use of the oxygen evolution catalyst according to claim 19 in the field of oxygen evolution reaction in electrolytic water, characterized in that, When the oxygen evolution catalyst is used as a catalyst for the oxygen evolution reaction at the anode of electrolytic water, in a 0.1 mol / L HClO4 solution, the current density is 100 mA / cm -2 After 400 h, the voltage does not increase significantly.

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